1. Field of the Invention
The present invention relates to a fixed blade assembly for a turbine or gas compressor.
A bladed stator for a turbine comprises an assembly of fixed blades arranged between inner and outer rings. FIGS. 1 and 2 show a monobloc stator with blades 1 between inner and outer rings 2 and 3.
2. Prior Art
The technologies normally employed for he manufacture of turbine stators involve casting and precision forging, whether it be for making monobloc bladed stators, or stators with assembled blades.
For operation at high temperatures, it can be envisaged to replace conventional metal or metal alloy blades with blades made of a refractory material.
However, it is difficult to envisage making the blades of solid ceramic especially sintered ceramic. Indeed, the inherent fragility of sintered ceramics limits their mechanical characteristics and resistance to thermal shocks. Accordingly, there would be difficult problems to solve in using such a material, especially as regards maintaining the blades between the inner and outer rings while avoiding any strain due to differential expansion.
For this reason, the present inventors have considered making blades using a thermostructural composite material.
Thermostructural composite materials are well known. They are formed from a refractory fibrous preform, such as carbon or ceramic fibers, densified by a refractory matrix, which may also be carbon or ceramic. Because of their fibrous reinforcement texture and their refractory composition, these materials possess good mechanical properties that make them suitable for use as structural elements, and retain their mechanical properties up to high temperatures, without exhibiting the fragility of solid ceramics.